Scotland Yard is facing fresh questions over the conduct of its officers after it revealed details of seven new complaints of alleged racism which it said it had referred to the police watchdog.

Speaking after a week in which the Metropolitan police came under pressure to clamp down on racism in its ranks, the Yard's deputy commissioner, Craig Mackey, said that seven further cases had been referred, or referred again, to the Independent Police Complaints Commission (IPCC). The move takes the total number of complaints under investigation to 10.

The Met has confirmed that 20 police officers and one police staff member were now under investigation for alleged racist incidents. Of those under investigation, eight police officers and the member of police staff have now been suspended, Scotland Yard has said. At least three other officers have been placed on restricted duties.

Declaring in a statement that there was "no room for racism in the Met", Mackey said the new referrals had been made as part of a review of racism allegations. All had already been "in the process of being considered" by Scotland Yard, he said, while four complaints had been re-referred to the IPCC.

A spokeswoman for the IPCC said the watchdog had not yet received the latest referrals and would "assess each case on its merits and make a decision regarding the level of IPCC involvement needed".

"At this stage the IPCC has not agreed to investigate any of these latest referrals," she added.

Three officers from Newham were already under investigation after reports by the Guardian of cases involving the alleged assault of a 15-year-old boy and the alleged racist abuse of a 21-year-old black man in the aftermath of the riots.

The seven new complaints made public include allegations of bullying, abuse and physical assault dating back as far as 2010. Claims include:

• Racist comments by another three Newham officers between January and March this year.

• Bullying by a number of police officers and staff against PCSOs over an 18-month period in Wandsworth.

• An assault involving five officers from the territorial support group against several youngsters in Hyde Park in 2011.

• A complaint from a member of the public of racial abuse by an unidentified police officer whilst in Camden in January.

• The mishandling of calls with a "racial element" by a PC in the force's central communication command in 2010.

In his statement, Mackey said: "The commissioner made it clear after the first alleged incident came to light last weekend that we take the issue of racism extremely seriously. I want to reiterate – there is no room for racism in the Met.

"Whilst any use of racist language is abhorrent, what is reassuring for me is that in the ten cases that have been referred to the IPCC, six involve other officers who have stood up and raised concerns, showing that we are an organisation that will not stand for any racist behaviour.

"These officers were not motivated to report their concerns by recent media coverage as this was done before this week."

On Thursday, IPCC commissioner Mike Franklin said he had asked the Met how it would ensure that allegations of racism were not more widespread.

Of the three suspensions, he added: "Naturally members of the public are going to have concerns that this again involves officers based in Newham borough and I have asked the Metropolitan Police Service what measures they have in place to ensure allegations of this nature are not more widespread. It is right that allegations of racism provoke public outcry which is why I have determined these allegations will receive the full independent scrutiny of the IPCC." In Newham, where the string of allegations have provoked shock, Superintendent Craig Haslam, acting borough commander of Newham, emaied local residents, saying that there was "no place for racism in the Metropolitan Police Service and here at Newham".

The force "absolutely determined to police the communities we serve with dignity, humanity, fairness and respect. Any failure to adhere to these standards of professionalism will not be tolerated.

"What we have heard over the last few days is of course completely at odds with all the close work that goes on with communities across London and in Newham every day."

Estelle du Boulay of the Newham Monitoring Project said: "This is very serious, and it goes back to what we said [last week] – that this is not unusual in terms of with the reports we get and the kind of cases we deal day-to-day.

"The only unusual thing about the first case was that this young man managed to capture it on his phone. For us it's finally some evidence that a culture of racism is embedded within the Metropolitan police."

She added that the prospect of an influx of police for the Olympics was "particularly worrying" for the borough.